A phase-locked loop (PLL) is a control system that tries to generate an output signal with a phase that is related to the phase of the input reference signal. The PLL circuit includes a variable frequency oscillator and a phase detector. The PLL circuit compares the phase of the input signal with the phase of the signal derived from its output oscillator and adjusts the frequency of its oscillator to keep the phases matched. The signal from the phase detector is used to control the oscillator in a feedback loop. The supply voltage of the PLL circuit is regulated with fixed voltage and does not change with frequency. This architecture consumes more power than is necessary.